Threatened Birds of the Americas
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STRIATED SOFTTAIL Thripophaga macroura V/R10 This poorly known ovenbird of lower canopy vine tangles occurs very patchily within a small range in lowland Atlantic Forest in south-east Brazil, where it appears to have suffered from much habitat destruction. DISTRIBUTION The Striated Softtail is endemic to the Atlantic Forest region of south-east Brazil from Bahia south of Salvador (no records since 1932) through eastern Minas Gerais (no records since 1969) to Espírito Santo and northern Rio de Janeiro state. Bahia The species was discovered by Wied (1820-1821) near the rio Catolé, an affluent of the rio Pardo (see Remarks), and it was subsequently found at the Engenho da Ponte, Aratuípe, where one female was collected in November 1932 (Pinto 1935), and in forest 11 km east of Boa Nova in August 1989 and July 1990 (B. C. Forrester in litt. 1992). Although no other precise localities have been recorded, at least 14 old trade skins in AMNH, ANSP, BMNH, FMNH, MCZ, MZUSP and USNM are labelled “Bahia”. Minas Gerais The only recorded localities are Machacalis, near the border of southern Bahia (not Espírito Santo as in Pinto 1978), where one female was obtained in December 1954 (in MZUSP), and Nanuque, where the species persisted until at least 1969 in the Mata da Cigana (G. T. de Mattos in litt. 1987). Espírito Santo Older records are (north to south) from the rio São José, September 1942; Lagoa Juparanã (in 1925 precisely at Santana), 120 m, August and September 1925, November 1929, and 1941/1942; rio Doce, March 1906 (Pinto 1938) and March 1956; Baixo Guandu (Fazenda da Serra), November 1925; Colatina, November 1940; Pau Gigante (now Ibiraçu), September 1940; Jatiboca (near Itarana), 900-1,000 m, May 1940; and Água Boa, Santa Cruz, October 1940 (specimens in AMNH, LACM, MNRJ, MZUSP, USNM). An untraced old record in the state is “Villa Alegre”, January 1912 (Cory and Hellmayr 1925). Recent records (all to the north of the rio São José) are mainly from the Sooretama Biological Reserve, with records almost annually from November 1980 to October 1990 (TAP), plus: November 1986 (J. F. Pacheco in litt. 1986), February 1987 (C. E. Carvalho in litt. 1987), August 1988 (M. Pearman in litt. 1990), September/October 1989 (B. M. Whitney and J. C. Rowlett in litt. 1990), July 1990 and January 1991 (Aleixo et al. 1991); and from the Córrego das Queixadas, Barra de São Francisco (close to the border of Minas Gerais), where two females were collected in December 1975 and July 1982 (G. T. de Mattos in litt. 1987). Rio de Janeiro Although one male was collected at Aldeia da Pedra (now Itaocara) on 5 July 1828 (Krabbe undated), this record remained overlooked and the state was never included in the species's range (e.g. Cory and Hellmayr 1925, Pinto 1938, 1978, Meyer de Schauensee 1982). Recently birds have been found at up to 800 m in the Desengano State Park, north-east of Santa Maria Madalena (J. F. Pacheco in litt. 1986, C. E. Carvalho in litt. 1987). POPULATION It seems evident that the species is now seriously reduced in abundance and distribution as a result of the extensive forest destruction which has taken place in its range (see Threats). It has been considered “locally not rare” (D. M. Teixeira in litt. 1987), “reasonably common” near Boa Nova (B. C. Forrester in litt. 1992; but see Threats) or even “still abundant” in an unprotected area in Barra de São Francisco (G. T. de Mattos in litt. 1987), but at Sooretama, though regularly recorded, birds are apparently restricted to a small portion within the forest (C. E. Carvalho in litt. 1987, Aleixo et al. 1991) or along forest edges where canopy vines are abundant (TAP). Through use of tape playback, as many as six pairs or families were easily encountered daily (during annual visits from 1980 to 1990) in the latter habitat along the north–south track through the western part of the reserve; however, pairs were very patchily distributed in the forest interior, again occurring where vine tangles were profuse (TAP). The Sooretama population is presumably fairly large, and failure to record the species to date from the adjacent CVRD Linhares Reserve is a cause of surprise (D. F. Stotz in litt. 1991) and a further indication of its apparent patchiness. ECOLOGY The Striated Softtail has been found in the interior of humid primary or little disturbed forest (Sick 1985, C. E. Carvalho in litt. 1987, G. T. de Mattos in litt. 1987), but also along forest edges (specimens in MNRJ, G. T. de Mattos in litt. 1987, TAP) and in degraded or secondary forest (G. T. de Mattos in litt. 1987, Aleixo et al. 1991). At Sooretama it was consistently noted in closely associating pairs or (family) groups of 3-5 individuals, two of which always responded vigorously to tape playback of BirdLife International (1992) Threatened Birds of the Americas. 1 Cambridge, UK: BirdLife International. Threatened birds of the Americas songs (male and female often sing antiphonally, as in the presumably closely related Plain Softtail Thripophaga fusciceps of western Amazonia) (TAP). Nearly all of more than 20 observations at that locality involved birds foraging in dense tangles of woody vines in the lower canopy (at 12-16 m) in c.25 m tall forest (TAP; see Population). Wied (1831-1833) also stressed the birds' use of low, thick, interconnecting growth, where it would keep to and call from the darkest, most tangled parts. Records are frequently of single birds or pairs in bird flocks (specimens in MNRJ; also Sick 1985, J. F. Pacheco in litt. 1986, C. E. Carvalho in litt. 1987, B. M. Whitney and J. C. Rowlett in litt. 1990). The species usually forages in pairs and perhaps family groups with mixed-species understorey flocks (typical members of which at Sooretama are Lesser Woodcreeper Lepidocolaptes fuscus, Plain Xenops Xenops minutus, Cinereous Antshrike Thamnomanes caesius, White-flanked Antwren Myrmotherula axillaris, the near-threatened Band-tailed Antwren M. urosticta and Olivaceous Flatbill Rhynchocyclus olivaceus; although at such times it particularly associates with the similar-looking bromeliad specialist Pale-browed Treehunter Cichlocolaptes leucophrus: TAP) in forest and older second growth, from about 2.5 to 7 m above ground, actively climbing in dense vine tangles (to which it generally keeps and in which it is difficult to observe), perch-gleaning arthropods from vines, twigs and branches, sometimes from leaves at the ends of branches (B. M. Whitney in litt. 1991); insects were in the stomachs of specimens in CGTM and MNRJ, and brownish, katydid-like orthopterans were seen removed from dead leaves by several individuals at Sooretama (TAP). Nesting has been recorded in Espírito Santo in September/October (B. M. Whitney and J. C. Rowlett in litt. 1990) and December (G. T. de Mattos in litt. 1987). The nest is a ball-shaped structure of dry twigs (or in one case possibly rootlets) built on the attenuating limbs of c.10 m tall trees in virgin forest or nearby on isolated trees; clutch-size is three (G. T. de Mattos in litt. 1987; also B. M. Whitney in litt. 1991). Territories apparently encompass a number of large trees covered with vines, and what were presumably the same pairs were encountered year after year at Sooretama within relatively small areas of less than 1.5 ha; in one area, at least three pairs held territories linearly spaced along a road through tall forest; pairs were usually separated by more than 100 m (TAP). THREATS The fragmentation of the species's range by extensive forest destruction has certainly had a major impact on its populations; the serious plight of forest around Boa Nova in central-southern Bahia is described in Threats under Slender Antbird Rhopornis ardesiaca. Although still present in degraded forests, the species is seemingly unable to survive in capoeira (young secondary growth) and other non- forest habitats (G. T. de Mattos in litt. 1987). Furthermore, the species is currently known from only a couple of protected areas, and its recorded numbers in these areas are too low to be confident about the future of the populations they hold. MEASURES TAKEN The Striated Softtail is protected under Brazilian law (Bernardes et al. 1990). Its occurrence in the 24,000 ha Sooretama Biological Reserve and in Desengano State Park is only partially reassuring, since the numbers observed remain so small and the species's ecological requirements are so poorly known. MEASURES PROPOSED Other remaining patches of forest within the species's range could still harbour small and so far undetected populations, and merit being identified and searched. Surveys of the species in the field are also needed to ascertain and monitor its status in the localities where it has been recorded. Support for the continued protection of these key sites is clearly imperative. REMARKS The rio Catolé, according to Wied's map, would be a small affluent of the left bank of the rio Cachoeira or Ilhéus; however, recent maps show it as a tributary of the left bank of the rio Pardo (Pinto 1938; also Bokerman 1957). 2 1992 Threat categories.